U.S. patent application number 13/442961 was filed with the patent office on 2012-11-01 for system and method of providing quick thermal comfort with reduced energy by using directed spot conditioning.
This patent application is currently assigned to DELPHI TECHNOLOGIES, INC.. Invention is credited to TIMOTHY D. CRAIG, DEBASHIS GHOSH, PRASAD S. KADLE, MINGYU WANG, EDWARD WOLFE, IV, MARK J. ZIMA.
Application Number | 20120276831 13/442961 |
Document ID | / |
Family ID | 46049182 |
Filed Date | 2012-11-01 |
United States Patent
Application |
20120276831 |
Kind Code |
A1 |
WANG; MINGYU ; et
al. |
November 1, 2012 |
System and Method of Providing Quick Thermal Comfort with Reduced
Energy by Using Directed Spot Conditioning
Abstract
A heating, ventilation, and air conditioning (HVAC) system and a
method of controlling a HVAC system that is configured to provide a
perceived comfortable ambient environment to an occupant seated in
a vehicle cabin. The system includes a nozzle configured to direct
an air stream from the HVAC system to the location of a thermally
sensitive portion of the body of the occupant. The system also
includes a controller configured to determine an air stream
temperature and an air stream flow rate necessary to establish the
desired heat supply rate for the sensitive portion and provide a
comfortable thermal environment by thermally isolating the occupant
from the ambient vehicle cabin temperature. The system may include
a sensor to determine the location of the sensitive portion. The
nozzle may include a thermoelectric device to heat or cool the air
stream.
Inventors: |
WANG; MINGYU; (AMHERST,
NY) ; KADLE; PRASAD S.; (WILLIAMSVILLE, NY) ;
GHOSH; DEBASHIS; (WILLIAMSVILLE, NY) ; ZIMA; MARK
J.; (CLARENCE CENTER, NY) ; WOLFE, IV; EDWARD;
(E. AMHERST, NY) ; CRAIG; TIMOTHY D.;
(WILLIAMSVILLE, NY) |
Assignee: |
DELPHI TECHNOLOGIES, INC.
TROY
MI
|
Family ID: |
46049182 |
Appl. No.: |
13/442961 |
Filed: |
April 10, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61479425 |
Apr 27, 2011 |
|
|
|
61499312 |
Jun 21, 2011 |
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Current U.S.
Class: |
454/75 |
Current CPC
Class: |
B60H 1/00742 20130101;
B60H 1/00871 20130101 |
Class at
Publication: |
454/75 |
International
Class: |
B60H 1/00 20060101
B60H001/00 |
Goverment Interests
GOVERNMENT LICENSE RIGHTS STATEMENT
[0002] This invention was made with the United States Government
support under Contract DE-EE0000014 awarded by the U.S. Department
of Energy. The Government has certain rights in this invention.
Claims
1. A heating, ventilation, and air conditioning (HVAC) system
configured to provide a perceived comfortable ambient environment
to an occupant seated in a vehicle cabin, said system comprising: a
first nozzle configured to direct a first air stream from the HVAC
system; a servo mechanism coupled to the first nozzle configured to
articulate the first nozzle in order to direct the first air stream
to a desired location; and a controller in communication with the
servo mechanism, said controller configured to identify a sensitive
portion of a body of the occupant that is more sensitive to heat
loss than other portions of the body, determine an ambient
temperature of the vehicle cabin, determine a desired heat supply
rate for the sensitive portion, wherein the desired heat supply
rate includes a steady-state heat supply rate based on a difference
between a comfortable heat loss rate for the sensitive portion and
an actual heat loss rate for the sensitive portion at the ambient
temperature; determine a comfortable skin temperature for the
sensitive portion, determine a flow rate for the first air stream
and a stream temperature for the first air stream based on at least
the desired heat supply rate, the comfortable skin temperature, a
discharge area of a nozzle, a dispersion angle of the nozzle, and a
distance from the first nozzle to the sensitive portion, determine
a location of the sensitive portion, and operate the servo
mechanism to articulate the first nozzle in order to direct the
first air stream to the location of the sensitive portion, said
first air stream characterized as having the stream temperature and
the flow rate necessary to establish the desired heat supply rate
for the sensitive portion.
2. The system of claim 1, wherein the desired heat supply rate
further includes a transient heat supply rate for the sensitive
portion, wherein the transient heat supply rate diminishes in
magnitude based on an elapsed time since a system start event.
3. The system of claim 1, wherein the controller includes a
database of temperature sensitivity of various body portions.
4. The system of claim 1, wherein the controller includes a
database of comfortable skin temperature for various body
portions.
5. The system of claim 1, wherein the system further comprises a
sensor configured to determine a seated height of the occupant,
wherein the sensor is in communication with the controller, wherein
the controller is configured to determine the location of the
sensitive portion based on the seated height indicated by the
sensor.
6. The system of claim 1, wherein the system further comprises a
sensor configured to determine a first seat position of a seat of
the occupant, wherein the sensor is in communication with the
controller, wherein the controller is configured to determine the
location of the sensitive portion based on the first seat position
indicated by the sensor.
7. The system of claim 1, wherein the controller is configured to
determine that a seat has moved from a first seat position to a
second seat position and determine a second location of the
sensitive portion based on the second seat position.
8. The system of claim 1, wherein the sensitive portion is a head
portion, and the first nozzle is a head nozzle, wherein the head
nozzle is characterized as having a head nozzle discharge area
between 1.25 and 12 square centimeters, a head nozzle to head
portion distance between 4 times a nozzle equivalent diameter and
10 times the nozzle equivalent diameter, a head nozzle flow rate
between 0.9 liters per second and 3.3 liters per second, and a head
nozzle stream temperature between 22.degree. C. and 26.degree.
C.
9. The system of claim 1, wherein the sensitive portion is a chest
portion, and the first nozzle is a chest nozzle, wherein the chest
nozzle is characterized as having a chest nozzle discharge area
between 1.25 and 20 square centimeters, a chest nozzle to chest
portion distance between 8 times a nozzle equivalent diameter and
15 times the nozzle equivalent diameter, a chest nozzle flow rate
between 3.8 liters per second and 7.6 liters per second, and a
chest nozzle stream temperature between 22.degree. C. and
26.degree. C.
10. The system of claim 1, wherein the sensitive portion is a lap
portion, and the first nozzle is a lap nozzle, wherein the lap
nozzle is characterized as having a lap nozzle discharge area
between 10 and 45 square centimeters, a lap nozzle to lap portion
distance between 8 times a nozzle equivalent diameter and 15 times
the nozzle equivalent diameter, a lap nozzle flow rate between 2.5
liters per second and 14.5 liters per second, and a lap nozzle
stream temperature between 22.degree. C. and 26.degree. C.
11. The system of claim 1, wherein the system further comprises: a
plurality of nozzles configured to direct a plurality of streams of
air from the HVAC system to a plurality of sensitive portions,
wherein a flow rate of at least one stream in the plurality of
streams of air is reduced effective to decrease energy consumed by
the HVAC system when energy available to the HVAC system is
reduced.
12. A method of controlling a heating, ventilation, and air
conditioning (HVAC) system to provide a perceived comfortable
ambient environment to an occupant seated in a vehicle cabin, said
method comprising the steps of: identifying a sensitive portion of
a body of the occupant that is more sensitive to heat loss than
other portions of the body; determining an ambient temperature of
the vehicle cabin; determining a desired heat supply rate for the
sensitive portion, wherein the desired heat supply rate includes a
steady-state heat supply rate based on a difference between a
comfortable heat loss rate for the sensitive portion and an actual
heat loss rate for the sensitive portion at the ambient
temperature; determining a comfortable skin temperature for the
sensitive portion; determining a flow rate for a stream of air and
a stream temperature for the stream based on at least the desired
heat supply rate, the comfortable skin temperature, a discharge
area of a nozzle, a dispersion angle of the nozzle, and a distance
from the nozzle to the sensitive portion; and operating the nozzle
to direct the stream to the location of the sensitive portion, said
stream characterized as having the stream temperature and the flow
rate necessary to establish the desired heat supply rate for the
sensitive portion.
13. The method of claim 12, wherein the desired heat supply rate
further includes a transient heat supply rate for the sensitive
portion, wherein the transient heat supply rate diminishes in
magnitude based on an elapsed time since a system start event.
14. The method of claim 12, wherein the step of identifying the
sensitive portion is based on a database of temperature sensitivity
of various body portions.
15. The method of claim 12, wherein the step of determining the
comfortable skin temperature for the sensitive portion is based on
a database of comfortable skin temperature for various body
portions.
16. The method of claim 12, said method further including the steps
of: determining a seat position of a seat of the occupant; and
determining the location of the sensitive portion based on the seat
position.
17. The method of claim 12, said method further including the steps
of: providing a plurality of nozzles configured to direct a
plurality of streams of air from the HVAC system to a plurality of
sensitive portions, wherein the desired heat supply rate for a more
sensitive portion is increased and the desired heat supply rate for
a less sensitive portion is decreased.
18. The method of claim 12, wherein the sensitive portion is a head
portion, said method further including the step of providing a head
nozzle configured to direct the stream toward the head portion,
said head nozzle characterized as having a head nozzle discharge
area between 1.25 and 12 square centimeters, a head nozzle to head
portion distance between 4 times a nozzle equivalent diameter and
10 times the nozzle equivalent diameter, a head nozzle flow rate
between 0.9 liters per second and 3.3 liters per second, and a head
nozzle stream temperature between 22.degree. C. and 26.degree.
C.
19. The method of claim 12, wherein the sensitive portion is a
chest portion, said method further including the step of providing
a chest nozzle configured to direct the stream toward the chest
portion, said chest nozzle characterized as having a chest nozzle
discharge area between 1.25 and 20 square centimeters, a chest
nozzle to chest portion distance between 8 times a nozzle
equivalent diameter and 15 times the nozzle equivalent diameter, a
chest nozzle flow rate between 3.8 liters per second and 7.6 liters
per second, and a chest nozzle stream temperature between
22.degree. C. and 26.degree. C.
20. The method of claim 10, wherein the sensitive portion is a lap
portion, said method further including the step of providing a lap
nozzle configured to direct the stream toward the lap portion, said
lap nozzle characterized as having a lap nozzle discharge area
between 10 and 45 square centimeters, a lap nozzle to lap portion
distance between 8 times a nozzle equivalent diameter and 15 times
the nozzle equivalent diameter, a lap nozzle flow rate between 2.5
liters per second and 14.5 liters per second, and a lap nozzle
stream temperature between 22.degree. C. and 26.degree. C.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit under 35 U.S.C.
.sctn.119(e) of U.S. Provisional Patent Application No. 61/479,425,
filed Apr. 27, 2011, the entire disclosure of which is hereby
incorporated herein by reference. This application also claims the
benefit under 35 U.S.C. .sctn.119(e) of U.S. Provisional Patent
Application No. 61/499,312, filed Jun. 21, 2011, the entire
disclosure of which is hereby incorporated herein by reference.
TECHNICAL FIELD OF INVENTION
[0003] The present disclosure relates to an occupant thermal
comfort system in a vehicle; more specifically, to a method of
providing quick thermal comfort by using spot conditioning portions
of the body of a vehicle occupant so the vehicle occupant perceives
that the ambient temperature is comfortable. As used herein, the
ambient temperature refers to the air temperature within the
vehicle cabin, distinct from the air temperature exterior to the
vehicle.
BACKGROUND OF INVENTION
[0004] Present vehicle heating, ventilation, and air conditioning
(HVAC) systems in vehicles are configured to maintain thermal
comfort of a vehicle occupant by providing a generally uniform
thermal environment of, for example, about 24.degree. C. within a
vehicle cabin under all outside environmental conditions. A
substantial percentage of the cooling or heating energy from the
HVAC system is used to bring the thermal mass within the vehicle
cabin to the desired temperature and to overcome the heat transfer
from the vehicle cabin to the outside environment.
SUMMARY OF THE INVENTION
[0005] In accordance with one embodiment of this invention, a
heating, ventilation, and air conditioning (HVAC) system that is
configured to provide a perceived comfortable ambient environment
to an occupant seated in a vehicle cabin is provided. The system
includes a first nozzle that is configured to direct a first air
stream from the HVAC system. The system also includes a servo
mechanism that is coupled to the first nozzle and is configured to
articulate the first nozzle in order to direct the first air stream
to a desired location. The system further includes a controller
that is in communication with the servo mechanism. The controller
is configured to identify a sensitive portion of a body of the
occupant that is more sensitive to heat loss than other portions of
the body, determine an ambient temperature of the vehicle cabin,
and determine a desired heat supply rate for the sensitive portion.
As used herein, a portion of the body refers to a portion of the
surface of the body, not an internal organ or an internal structure
of the body. As used herein, the desired heat supply rate provides
heating when it is positive in value, and supplies cooing when it
is negative in value.
[0006] The desired heat supply rate includes a steady-state heat
supply rate based on a difference between a comfortable heat loss
rate for the sensitive portion and an actual heat loss rate for the
sensitive portion at the ambient temperature. The desired heat
supply rate may further include a transient heat supply rate for
the sensitive portion. The transient heat supply rate may diminish
in magnitude based on an elapsed time since a system start event.
The controller is further configured to determine a comfortable
skin temperature for the sensitive portion, determine a flow rate
for a first air stream and a stream temperature for the first air
stream. The flow rate and the stream temperature are based on, at
least, the desired heat supply rate, the comfortable skin
temperature, a discharge area of a nozzle, a dispersion angle of
the nozzle, and a distance from the nozzle to the sensitive
portion. The controller is also configured to determine a location
of the sensitive portion and operate the servo mechanism to
articulate the first nozzle in order to direct the first air stream
to the location of the sensitive portion. The first air stream is
characterized as having the stream temperature and the flow rate
necessary to establish the desired heat supply rate for the
sensitive portion.
[0007] In another embodiment of the present invention, the system
further includes a sensor that is configured to determine a seated
height of the occupant. The sensor is in communication with the
controller. The controller is configured to determine the location
of the sensitive portion based on the seated height indicated by
the sensor.
[0008] In another embodiment of the present invention, the system
further includes a sensor configured to determine a first seat
position of a seat of the occupant. The sensor is in communication
with the controller. The controller is configured to determine the
location of the sensitive portion based on the first seat position
indicated by the sensor.
[0009] In another embodiment of the present invention, the
controller is configured to determine that a seat has moved from a
first seat position to a second seat position and determine a
second location of the sensitive portion based on the second seat
position.
[0010] In yet another embodiment of the present invention, a method
of controlling a heating, ventilation, and air conditioning system
to provide a perceived comfortable ambient environment to an
occupant seated in a vehicle cabin is provided. The method includes
the steps of identifying a sensitive portion of a body of the
occupant that is more sensitive to heat loss than other portions of
the body, determining an ambient temperature of the vehicle cabin,
and determining a desired heat supply rate for the sensitive
portion. The desired heat supply rate includes a steady-state heat
supply rate based on a difference between a comfortable heat loss
rate for the sensitive portion and an actual heat loss rate for the
sensitive portion at the ambient temperature. The desired heat
supply rate may further include a transient heat supply rate for
the sensitive portion. The transient heat supply rate may diminish
in magnitude based on an elapsed time since a system start event.
The method also includes the steps of determining a comfortable
skin temperature for the sensitive portion and determining a flow
rate for a stream of air and a stream temperature for the stream
based on at least the desired heat supply rate, the comfortable
skin temperature, a discharge area of a nozzle, a dispersion angle
of the nozzle, and a distance from the nozzle to the sensitive
portion. The method further includes the steps of determining a
location of the sensitive portion and operating the nozzle to
direct the stream to the location of the sensitive portion. The
stream is characterized as having the stream temperature and the
flow rate necessary to establish the desired heat supply rate at
the sensitive portion.
[0011] Further features and advantages of the invention will appear
more clearly on a reading of the following detailed description of
the preferred embodiment of the invention, which is given by way of
non-limiting example only and with reference to the accompanying
drawings.
BRIEF DESCRIPTION OF DRAWINGS
[0012] The present invention will now be described, by way of
example with reference to the accompanying drawings, in which:
[0013] FIG. 1 is a graph illustrating a relative thermal
sensitivity of various human body portions in a high ambient
temperature environment;
[0014] FIG. 2 is a graph illustrating a relative thermal
sensitivity of various human body portions in a low ambient
temperature environment;
[0015] FIG. 3 is a graph illustrating a difference between actual
heat loss rates of various body portions in an environment between
6.degree. C. and 24.degree. C., and the comfortable heat loss rates
occurring nominally at 24.degree. C.;
[0016] FIG. 4 is a graph illustrating transient over-conditioning
of a sensitive portion and the resultant perceived thermal
sensation;
[0017] FIG. 5 is a graph illustrating continued over-conditioning
of a sensitive portion and the resultant perceived thermal
sensation;
[0018] FIG. 6 is a cutaway side view diagram of a vehicle equipped
with an HVAC system configured to provide a perceived comfortable
ambient environment to an occupant in accordance with one
embodiment;
[0019] FIG. 7 is a side view of a nozzle and a servo mechanism of
an HVAC system in accordance with one embodiment; and
[0020] FIG. 8 is a flow diagram of a method for controlling an HVAC
system in accordance with another embodiment.
DETAILED DESCRIPTION OF INVENTION
[0021] The thermal comfort of a vehicle occupant in a vehicle cabin
may be primarily determined by the heat loss rate of the occupant.
The occupant may typically be comfortable in an ambient temperature
of about 24.degree. C. Therefore, when the heat loss rate of the
occupant is higher than when in an environment with an ambient
temperature of 24.degree. C., the occupant tends to feel cooler.
When the heat loss rate of the occupant is lower than when in an
environment with an ambient temperature of 24.degree. C., the
occupant tends to feel warmer.
[0022] Rather than maintaining the entire vehicle cabin at a
comfortable ambient temperature of 24.degree. C., it may be
advantageous to just maintain the heat loss rate of the occupant at
a rate that is equivalent to an ambient temperature of 24.degree.
C. (the desired or comfortable heat loss rate). The vehicle
occupant may be effectively thermally isolated from the ambient
temperature of the vehicle cabin by directing thermal energy to the
vehicle occupant, in a non-limiting example by directing an air
stream at a specific temperature and air flow rate so that the heat
loss rate of the occupant is generally the same as would occur at
an ambient temperature of 24.degree. C. Alternatively, thermal
energy may be directed toward the vehicle occupant by radiant,
convective, or conductive means. The air stream may effectively
isolate the occupant from the vehicle cabin ambient
temperature.
[0023] Since the air stream may effectively thermally isolate the
occupant from the vehicle cabin thermal environment, it may be
possible to save energy by maintaining a higher ambient temperature
(for situations when cooling is desired) or a lower ambient
temperate (for situations when heating is desired) within the
vehicle cabin. Is has been estimated that a 5% energy savings may
be realized for every 1.degree. C. increase in the ambient
temperature of the vehicle cabin when cooling is desired. Energy
savings for heating cabins of vehicles with internal combustion
(IC) engines are usually lower since the energy used for heating is
typically waste heat from the IC engine. However, in electrical
vehicles that do not create a significant amount of waste heat,
energy from the vehicle batteries must be supplied to heat the
vehicle cabin; therefore similar energy savings for heating may be
realized.
[0024] It has been observed that different portions or areas of a
human body have different sensitivity to heat loss caused by the
ambient temperature. For example, the human face is relatively
insensitive to cold ambient temperatures within a reasonable range,
while other body portions, such as feet have higher sensitivity to
cold ambient temperatures. Therefore, it may be advantageous to
direct thermal energy to portions of the occupant's body that are
most sensitive, as a non-limiting example providing spot
conditioning. As used herein, spot conditioning means directing a
stream of air at a specific temperature and flow rate toward a
sensitive portion of the occupant's body to provide a heat loss
rate for the sensitive portion equivalent to the heat loss rate at
a comfortable temperature, such as 24.degree. C.
[0025] A model of a human body identifying thermal sensation and
thermal comfort sensitivity of various body portions to temperature
has been developed to determine which body portions to heat or cool
to achieve thermal comfort through spot conditioning. As an
illustrative example, the static local sensation equation by Zhang
et al. ["Thermal Sensation and Comfort Models for Non-Uniform and
Transient Environments: Part I: Local Sensation of Individual Body
Parts", Indoor Environmental Quality (IEQ), Center for the Built
Environment, Center for Environmental Design Research, University
of California--Berkeley, 2009] may be used to determine the
sensitivity of body portions to localized heating or cooling.
[0026] According to Zhang et al., ibid, a local static thermal
sensation index for each body portion may be correlated to skin
temperature via the following equation,
LTI=4*((2/1+e (-C1*(Tsk-Tskc)-K1*((Tsk-Tskc)-(Tavg-Tavgc)))-1)
LTI is the local thermal sensation index for a particular body
portion. The value of the index ranges between -4 (very cold) to 4
(very hot) with zero (0) corresponding to a natural or comfortable
thermal sensation. Tsk is the actual skin temperature of the
particular body portion, Tskc is the comfortable skin temperature
for that body portion, Tavg is the average skin temperature for the
body and Tavgc is the average skin temperature for the body at a
comfortable ambient temperature. The coefficient C1 represents the
sensitivity to the skin temperature changes determined by a given
ambient temperature. As non-limiting example, the coefficient C1
may be used as a selection criterion for sensitive body
portions.
[0027] FIG. 1 illustrates the coefficient C1 for various body
portions in high ambient temperature conditions, thus being
relevant to cooling. It can be seen that the forehead, neck, chest,
back and lower arms are the more sensitive body portions to
temperature in warmer environments and may be considered for spot
conditioning for occupant cooling.
[0028] FIG. 2 illustrates the coefficient C1 for various body
portions in low ambient temperature conditions which are pertinent
to comfort heating. It can be seen that the forehead, neck, chest,
back, lower arms and legs are the more sensitive body portions to
temperature in cooler environments may be considered for spot
conditioning for occupant heating.
[0029] Depending on the strictness of the comfort maintenance
requirements, more or fewer body portions may be selected for spot
conditioning. Better thermal comfort may be achieved by spot
conditioning of more of the body portions, while better energy
efficiency of the HAVC system may be achieved by spot conditioning
fewer body portions.
[0030] For an electrical vehicle (EV) or plug-in hybrid electric
vehicle (PHEV), it may be possible to correlate the number of spot
conditioned body portions to the remaining battery capacity or to
the electric driving range. When electric driving range is of
primary concern, spot conditioning may be delivered to fewer
sensitive portions. As the battery is being depleted, the number of
sensitive portions spot conditioned can be further reduced.
[0031] Human thermal comfort may be best achieved at an ambient air
temperature of 24.degree. C., and may be used as a baseline for
heat loss rate. In this comfortable thermal environment, body
portions dissipate heat generated by metabolic activities to the
environment. The heat loss rate at 24.degree. C. is a comfortable
heat loss rate that may be designated as Qc. The actual heat loss
rate for various body portions at various ambient temperatures may
be determined experimentally or through computational fluid
dynamics analysis.
[0032] When the ambient temperature is lower than the reference
ambient temperature of 24.degree. C., the heat loss rate from the
various body portions will be greater than the baseline rate at
24.degree. C. At the ambient temperature of Ta, the actual heat
loss rate may be designated Qact. The difference Qss between the
comfortable heat loss rate Qc and the actual heat loss rate Qact is
the rate at which thermal energy must be delivered to a particular
body portion to maintain comfort in steady-state conditions. As
used herein, Qss is referred to as the desired steady state heat
supply rate.
[0033] FIG. 3 illustrates the difference between the heat loss rate
Qact and the comfortable heat loss rate Qc for various body
portions as the ambient temperature increases from 6.degree. C. to
24.degree. C. As the ambient temperature decreases, the actual heat
loss rate of each body portion increases and more heating is
required for the body portions to remain comfortable. Similar
graphs may be generated for temperatures above 24.degree. C. For
steady-state thermal comfort, comfort maintenance requirement may
be met when the heating or cooling delivered is equal to the
difference between the heat loss rate Qact and the comfortable heat
loss rate Qc.
[0034] FIG. 4 illustrates that it may be desirable to provide
over-conditioning of the sensitive portions by modifying the
desired heat supply rate to achieve quicker comfort for an initial
time period before scaling back to the steady-state heat supply
rate Qss. As used herein, over-conditioning means providing a heat
supply rate for the sensitive portion greater than the steady-state
heat supply rate to achieve overall thermal comfort quickly. In the
non-limiting example shown in FIG. 4, heating is delivered to the
sensitive portion provide an initial over-heating of the sensitive
portion before scaling back to steady state heating. The initial
heat supply rate is greater than the steady state heat supply rate
by the amount represented by Qt. The amount of heating delivered to
the sensitive portion is reduced over time until the heat supply
rate of the sensitive portion is equal to the steady state heat
supply rate. This may be beneficial when the occupant enters a cold
soaked car on a cold winter night. Alternately, providing a greater
negative heat supply rate than the steady-state supply rate may be
beneficial when the occupant enters a hot soaked car on a high
temperature summer day with strong solar exposure. Therefore the
desired heat supply rate (Qd) may include a steady-state component
(Qss) and a transient component (Qt).
[0035] FIG. 5 illustrates that for energy efficient operation of
the HVAC system and enhanced comfort in steady-state operation, the
number of the spot conditioned body portions may be reduced by
focusing on a few of the most thermally sensitive portions, instead
of all the body portions, and over-condition only the selected
sensitive portions. In the non-limiting example shown in FIG. 5, a
number of sensitive portions may be over-conditioned beyond basic
comfort during the transient phase of the spot conditioning to such
an extent that the sensitive portions may feel slightly overheated
when the system is providing heating. Additionally, when the
vehicle cabin achieves a steady state ambient temperature, instead
of returning to a neutral thermal state (i.e. where the heat supply
rate is equal to the difference between Qc and Qact), the sensitive
portions may remain slightly over-conditioned to allow the cabin
ambient temperature control to be more relaxed (under-conditioned),
so that both improved overall body comfort and reduced overall
energy consumption may be obtained due to the smaller body portion
set. A number of sensitive portions may be similarly
over-conditioned for cooling.
[0036] FIG. 6 illustrates a non-limiting example of a heating,
ventilation, and air conditioning system 10 that is configured to
provide a perceived comfortable ambient environment to an occupant
12 seated in a cabin 14 of a vehicle 16. The system 10 includes a
first nozzle 18 that is configured to direct a first air stream 20
from the HVAC system 10. The system 10 may also include an air
plenum 22 that is configured to direct air that has been heated or
cooled by a heat exchanger 24, such as an evaporator, a heater
core, or a thermoelectric device within the HVAC system 10 to the
first nozzle 18. The system 10 may further include an air movement
device such as a fan to force air from the cabin 14 or outside of
the vehicle 16 through the heat exchanger 24 and through the first
nozzle 18.
[0037] Alternatively, the HVAC system 10 may include a
thermoelectric device that is disposed in proximity to the first
nozzle 18. The thermoelectric device may be configured to heat or
cool air drawn though the hvac system 10. The HVAC system 10 may
also include a fan or another air movement device that is
configured to draw vehicle cabin 14 air into the HVAC system 10 and
force it past the thermoelectric device and through the first
nozzle 18.
[0038] FIG. 7 illustrates a non-limiting example of the first
nozzle 18 that includes a servo mechanism 26 that is mechanically
coupled to the first nozzle 18. The servo mechanism 26 is
configured to articulate the first nozzle 18 in order to direct the
first air stream 20 to a desired location within the vehicle cabin
14. As used herein, articulate refers to moving the nozzle in one
or more axes in order to direct the first air stream 20. The first
nozzle 18 may have freedom of movement in one or preferably two
axes, such as when mounted in a gimbal device. The nozzle may also
be configured to move fore and aft, that is extend and retract as
well as move up/down and right/left. The servo mechanism 26 may
include a servo motor with a ball and screw drive or a stepper
motor. The servo mechanism 26 may be configured to maintain
direction of the first air stream 20 to the desired location, such
as a specific portion of the body of the occupant 12 rather than
sweep the first air stream 20 over various portions of the body of
the occupant 12.
[0039] The first nozzle 18 may also be a fixed nozzle that is
configured to direct the first air stream 20 to a single location
within the vehicle cabin 14. A dispersion angle of the first nozzle
18 may be selected so that the first air stream 20 covers the
sensitive portion 30 of an occupant 12 ranging from a 10.sup.th
percentile female occupant to a 90.sup.th percentile male occupant.
The first nozzle 18 may also be configured to be manually directed
toward the sensitive portion 30 by the occupant 12, without the
servo mechanism 26 articulating the first nozzle 18 in order to
direct the first air stream 20 to the location of the sensitive
portion 30.
[0040] Referring again to FIG. 6, the HVAC system 10 further
includes a controller 28 in communication with at least the servo
mechanism 26. The controller 28 may include a microprocessor or
application specific integrated circuit (ASIC) configured to
control the servo mechanism 26. Software that configures the
microprocessor or ASIC to control the servo mechanism 26 may be
stored in non-volatile (NV) memory within the controller 28.
Non-limiting examples of the types of NV memory that may be used
include electrically erasable programmable read only memory
(EEPROM), masked read only memory (ROM) and flash memory. The
controller 28 may also include analog to digital (A/D) convertor
circuits and digital to analog (D/A) convertor circuits to allow
the convertor to establish electrical communication with the servo
mechanism 26 and other electronic devices, such as sensors.
[0041] The software may also include instructions that, when
executed, cause the controller 28 to identify a sensitive portion
30 of a body of the occupant 12 that is more sensitive to heat loss
than other portions of the body. The sensitive portion 30
identified may depend whether the occupant 12 is in a high ambient
temperature environment where the heat loss rate needs to be
increased to maintain comfort, that is the system 10 is providing
cooling of the occupant 12 or in a lower ambient temperature
environment where the heat loss rate needs to be lowered in order
to maintain comfort, that is the system 10 is providing heating to
the occupant 12. In a non-limiting example, in a higher ambient
temperature environment the sensitive portion 30 may be, in order
of decreasing sensitivity, a forehead portion 30, a neck portion
32, a chest portion 34, a lower arm portion 36, a face portion 38,
a pelvis portion 40, an upper arm portion 42, a hand portion 44, a
lower leg portion 46, a thigh portion 48 or a foot portion 50. In
another non-limiting example, in a lower ambient temperature
environment the sensitive portion 30 may be, in order of decreasing
sensitivity, a forehead portion 30, a neck portion 32, a chest
portion 34, a lower arm portion 36, an upper arm portion 42, a
lower leg portion 46, a foot portion 50, a pelvis portion 40, a
hand portion 44, a thigh portion 48, or a face portion 38.
[0042] The identification of sensitive body portions may be based
upon models of the human body such as the Human Thermal Comfort
Model developed by Zhang et al., ibid to determine thermal comfort
sensitivity of body portions to the ambient temperature. The
controller 28 may include a database of the temperature sensitivity
of various body portions stored in the memory of the controller
28.
[0043] The controller 28 is configured to determine an ambient
temperature of the vehicle cabin 14. The system 10 may include a
temperature sensor 52 that is disposed within the vehicle cabin 14.
The controller 28 may be in electrical communication with the
temperature sensor 52. The temperature sensor 52 may be configured
to measure the ambient air temperature within the cabin 14.
Alternatively, the system 10 may include a plurality of temperature
sensors in order to determine a local ambient temperature in
various location of the vehicle cabin 14 and/or to determine an
average ambient temperature.
[0044] The controller 28 is configured to determine a desired heat
supply rate (Qd) for the sensitive portion 30. The desired heat
supply rate includes a steady-state heat supply rate (Qss) and a
transient heat supply rate (Qt). The desired heat supply rate may
be determined by the formula Qd=Qss+Qt.
[0045] The steady-state heat supply rate is based on a difference
between the comfortable heat loss rate (Qc) for the sensitive
portion 30 and an actual heat loss rate (Qact) for the sensitive
portion 30 at the ambient temperature. The steady-state heat supply
rate may be determined by the formula Qss=Qc-Qact. The controller
28 may include a database containing the comfortable heat loss rate
(Qc) for each of the sensitive portions database stored in the
memory of the controller 28. The controller 28 may also include a
database stored in the memory of the controller 28 containing and
the actual heat loss rate (Qact) for each of the sensitive portions
at various ambient temperatures. The controller 28 may be
configured to interpolate a value for the actual heat loss rate
when the ambient temperature is not contained in the database.
Alternatively, the HVAC system 10 may include a thermal sensor,
such as an infrared imaging sensor, in communication with the
controller 28. The thermal sensor may be configured to determine
the actual heat loss rate (Qact) of the sensitive portion 30.
[0046] The transient heat supply rate may diminish in magnitude
based on an elapsed time since a system 10 start event. The
transient heat supply rate may be determined by the formula
Qt=Qdelta(1-e (-ct)), where Qdelta is typically less than 100% of
the steady-state heat supply rate Qss. Qdelta may be a function of
the initial ambient temperature within the vehicle cabin 14. e is
the mathematic constant `e`, also known as Euler's number or
Napier's constant, c is a calibrateable time constant, and t is the
elapsed time since the system 10 start event. The value of the time
constant c is typically based upon the value of Qdelta and the
initial ambient temperature within the vehicle cabin 14. The
diminishing of the transient heat supply rate may alternatively be
based on other mathematical formulae.
[0047] The controller 28 is further configured to determine a
comfortable skin temperature for the sensitive portion 30 of the
body of the occupant 12. The comfortable skin temperature may also
be based on models of the human body such as the Human Thermal
Comfort Model developed by Zhang et al., ibid. The controller 28
may include a database of comfortable skin temperatures for various
body portions stored in the memory of the controller 28 database
stored in the memory of the controller 28.
[0048] The controller 28 is configured to determine a flow rate for
a first air stream 20 discharged from the HVAC system 10 and a
stream temperature for the first air stream 20 discharged from the
HVAC system 10. The flow rate and stream temperature are based on
at least the desired heat supply rate, the comfortable skin
temperature, a discharge area of a nozzle, a dispersion angle of
the nozzle, and a distance from the nozzle to the sensitive portion
30. The flow rate and the stream temperature may be determined by
the formula Qd=K*(Rf*(Tst-Tskc/A*alpha*L), where Qd is the desired
heat supply rate, Tst is the stream temperature, Rf is the flow
rate, Tskc is the comfortable skin temperature, A is a discharge
area of the nozzle, alpha is the dispersion angle of the nozzle, L
is the distance from the nozzle to the sensitive portion 30, and K
is a calibration constant. The value of the calibration constant K
may be determined experimentally and is dependent on the stream
temperature and the flow rate. It is to be noted that there may be
a multitude of combinations of flow rate and stream temperature
that can provide the desired heat supply rate. The flow rate and
stream temperature may also be bounded because flow rates that are
too high as well as stream temperatures that are too high or too
low may cause discomfort to the occupant 12.
[0049] The distance (L) from the first nozzle 18 to the sensitive
portion 30 needs to be optimized. As the first air stream 20 passes
through the vehicle cabin 14, air that is at the ambient
temperature may be entrained in the first air stream 20. As the
distance L increases, more cabin air may be entrained in the first
air stream 20 which may significantly alter the temperature of the
first air stream 20 delivered to the sensitive portion 30. As the
distance L decreases, the surface velocity of the first air stream
20 on the sensitive portion 30 may be high enough to cause
discomfort to the occupant 12.
[0050] The controller 28 is configured to determine a location of
the sensitive portion 30 within the vehicle cabin 14. The
controller 28 may include a database of location information of the
sensitive body portions in relation to the first nozzle 18, as a
non-limiting example azimuth and distance information. The
controller 28 may utilize this location information to command the
servo mechanism 26 to direct the first nozzle 18 to deliver the
first air stream 20 to a sensitive portion 30 of the body of the
occupant 12. The location information may be generalized so that
the location information encompasses the location of the sensitive
portion 30 of a female occupant in the 10.sup.th percentile of
height and a male occupant in the 90.sup.th percentile of
height.
[0051] Continuing to refer to FIG. 6, the system 10 may further
include a sensor 54 that is configured to determine a seated height
of the occupant 12. The seated height sensor 54 may be in
communication with the controller 28. The controller 28 may be
configured to determine the location of the sensitive portion 30 of
the body of the occupant 12 based on the seated height indicated by
the seated height sensor 54. The controller 28 may include a
database of location information of the sensitive body portions
correlated to the seated height of the occupant 12. Such a database
may be generated based on anthropometric data, such as that
contained in Chapter 11 of "Human Engineering Guide to Equipment
Design" Harold P Van Cott and Robert G Kinkade, ed., American
Institutes for Research, 1972. The seated height sensor 54 may
provide an advantage of directing the first air stream 20 more
precisely to the sensitive portion 30. This may allow the first
nozzle 18 to have a narrower dispersion angle, which will reduce
the entrainment of ambient cabin air in the first air stream 20. It
may also allow the flow rate of the first air stream 20 to be
reduced, thereby reducing energy required for an air movement
device and beneficially reducing noise from the HVAC system 10.
[0052] The system 10 may further include a sensor 56 configured to
determine a first seat position 58 of a seat of the occupant 12.
The seat position sensor 56 may be in communication with the
controller 28. The controller 28 may be configured to determine the
location of the sensitive portion 30 based on the first seat
position 58 indicated by the seat position sensor 56. The
controller 28 may be further configured to determine a leg length
of the occupant 12 based on the seat position of the occupant 12
and determine the location of the sensitive portion 30 based on the
leg length of the occupant 12. The controller 28 may include a
database of leg length of the occupant 12 based on seat position
and location information of the sensitive body portions correlated
to the leg length of the occupant 12. Such a database may be
generated based on anthropometric data, such as that contained in
Chapter 11 of "Human Engineering Guide to Equipment Design", ibid.
The seat position sensor 56 may provide an advantage of directing
the first air stream 20 more precisely to the sensitive portion 30.
This may allow the first nozzle 18 to have a narrower dispersion
angle, which will reduce the entrainment of ambient cabin air in
the first air stream 20. It may also allow the flow rate of the
first air stream 20 to be reduced, thereby reducing energy required
for an air movement device and beneficially reducing noise from the
HVAC system 10.
[0053] The controller 28 may be configured to determine that a seat
has moved from a first seat position 58 to a second seat position
60 and determine a second location 62 of the sensitive portion 30
based on the second seat position 60.
[0054] The controller 28 is configured to operate the servo
mechanism 26 to articulate the first nozzle 18 in order to direct
the first air stream 20 to the location of the sensitive portion
30. The first air stream 20 discharged from the HVAC system 10 is
characterized as having the stream temperature and the flow rate
necessary to establish the desired heat supply rate at the
sensitive portion 30 to heat or cool the occupant 12 in order to
provide a perceived comfortable ambient environment to the occupant
12 seated in the vehicle cabin 14.
[0055] When the desired heat supply rate is established for the
sensitive portion 30 through spot conditioning, the sensitive
portion 30 may be effectively thermally isolated from the ambient
temperature in the vehicle cabin 14. Therefore, it may no longer be
necessary to maintain the entire cabin 14 at a comfortable ambient
temperature of 24.degree. C. in order provide thermal comfort for
the sensitive portion 30. The vehicle ambient temperature may be
maintained at a temperature higher (for cooling) or lower (for
heating) while still maintaining occupant comfort. This may provide
a benefit of reducing HVAC system energy consumption because less
energy may be expended for maintaining the vehicle cabin
temperature. There may also be less energy expended brining the
thermal mass of the cabin 14 to the cabin ambient temperature.
[0056] For example, typically an energy saving of 5% per 1.degree.
C. increase over 24.degree. C. in cabin temperature may be realized
in automotive air conditioning (cooling) systems. The energy
required to cool the first air and provide the first flow rate may
be much less than the energy saved by increasing the cabin ambient
temperature. Similar savings may be seen in electric vehicles by
decreasing the cabin temperature for heating. Unlike IC engine
vehicles that use engine waste heat to heat the vehicle cabin 14,
electric vehicles typically use energy from the vehicle batteries
to heat the cabin 14.
[0057] The first nozzle 18 may be preferably configured to deliver
a substantially laminar flow rather than a turbulent flow in order
to minimize entrainment of ambient air that may alter the
temperature and the flow rate of the first air stream 20 delivered
to the sensitive portion 30.
[0058] The first nozzle 18 may also include a nozzle control device
in order to control the flow rate, discharge area, or dispersion
angle of the nozzle. The nozzle control device may be an iris
within the nozzle.
[0059] Based on test results, it was determined that the optimum
distance from the first nozzle 18 to the sensitive portion 30 (L)
was dictated by air entrainment and air flow spread on the
sensitive portion 30. If the first nozzle 18 was positioned too far
from the sensitive portion 30, then the first air stream 20
contained enough entrained cabin air at the ambient temperature to
significantly reduce the efficacy of the spot conditioning. The
distance (L) in combination with the dispersion angle (alpha)
determined the air flow spread on the sensitive portion 30. The
first nozzle 18 was configured to have a wide air flow spread on
the sensitive portion 30.
[0060] Based on test results, air impingement velocities of the
first air stream 20 on the sensitive portion 30 also need to be
considered. Air impingement velocities, especially when the
sensitive portion 30 was the face portion 38, were considered
uncomfortable by the occupant 12 when velocities were too high.
Also, the first air stream 20 was considered to be less comfortable
when the first air flow was flowing up over the face portion 38
rather than flowing down over the face portion 38.
[0061] As illustrated in FIG. 6, the sensitive portion 30 may be a
head portion 64. The head portion 64 may include the face portion
38 and the forehead portion 30. The first nozzle 18 may be a head
nozzle 18. The first air stream 20 from the head nozzle 18 may be a
head air stream 20 and may encompass both the face portion 38 and
the forehead portion 30. The head nozzle 18 may be characterized as
having a head nozzle 18 discharge area between 1.25 and 12 square
centimeters and a head nozzle to head portion distance between 4
times a nozzle equivalent diameter and 10 times the nozzle
equivalent diameter. For cooling, a head nozzle 18 flow rate may
preferably be between 0.9 liters per second (2 cubic feet per
minute (CFM) and 3.3 liters per second (12 CFM) and a head nozzle
18 stream temperature may preferably be between 22.degree. C. and
26.degree. C. The head nozzle 18 is preferably configured so that
the first air stream 20 flows down (from forehead to chin) over the
face portion 38 rather than up (from chin to forehead) over the
face portion 38.
[0062] The head nozzle 18 may be preferably disposed above the head
of the occupant 12 within the vehicle cabin 14. The head nozzle may
be located in a headliner of the vehicle cabin 14. The head nozzle
18 may also be located in an overhead console in the vehicle cabin
14.
[0063] The nozzle equivalent diameter for a nozzle with a circular
discharge portion is the actual diameter of the discharge portion.
The nozzle equivalent diameter (Dh) for a nozzle with a discharge
portion with a shape that is other than circular is 4 times the
area of the discharge portion (A) divided by the perimeter of the
discharge portion (P), that is Dh=4A/P, also known as the hydraulic
diameter.
[0064] Based on test results, it was determined that satisfactory
cooling in a vehicle cabin 14 with an ambient temperature of
28.degree. C. and 31.degree. C. was achieved by directing separate
air streams to at least one of the head portion 64, the chest
portion 34, and the lap portion 70 where the nozzle discharge
areas, nozzle to portion distance, flow rates and stream
temperatures are as characterized infra.
[0065] The sensitive portion 30 may be the chest portion 34 and the
first nozzle 18 may be a chest nozzle 66. The first air stream 20
from the chest nozzle 66 may be a chest air stream 68. The chest
nozzle 66 may be characterized as having a chest nozzle discharge
area between 1.25 and 20 square centimeters and a chest nozzle to
chest portion distance between 8 times a nozzle equivalent diameter
and 15 times the nozzle equivalent diameter. For cooling, a chest
nozzle flow rate may preferably be between 3.8 liters per second (8
CFM) and 7.6 liters per second (16 CFM) and a chest nozzle stream
temperature may preferably be between 22.degree. C. and 26.degree.
C. For heating, a chest nozzle flow rate may preferably be between
3.8 liters per second (5 CFM) and 7.6 liters per second (12 CFM)
and a chest nozzle stream temperature may preferably be between
30.degree. C. and 45.degree. C. The chest nozzle may be located
within an instrument panel.
[0066] The chest nozzle 66 may be preferably disposed in front of
the occupant 12 within the vehicle cabin 14. The chest nozzle 66
may be located in an instrument panel or in the headliner of the
vehicle 16. The chest nozzle 66 may be located within a seat back
when the occupant 12 is sitting in a rear seat or a third row seat
of the vehicle 16.
[0067] The sensitive portion 30 may be a lap portion 70. The lap
portion 70 may include the pelvis portion 40 and the thigh portion
48. The first nozzle 18 may be a lap nozzle 72. The first air
stream 20 from the lap nozzle 72 may be a lap air stream 74. The
lap nozzle 72 may be characterized as having a lap nozzle 72
discharge area between 10 and 45 square centimeters and a lap
nozzle to lap portion distance between 8 times a nozzle equivalent
diameter and 15 times the nozzle equivalent diameter. For cooling,
a lap nozzle flow rate may preferably be between 2.5 liters per
second (5.3 CFM) and 14.5 liters per second (30 CFM) and a lap
nozzle stream temperature may preferably be between 22.degree. C.
and 26.degree. C. For heating, the lap nozzle flow rate may
preferably be between 3 liters per second (6 CFM) and 14.5 liters
per second (30 CFM) and the lap nozzle stream temperature may
preferably be between 30.degree. C. and 45.degree. C.
[0068] The lap nozzle 72 may be preferably disposed in front of the
occupant 12 within the vehicle cabin 14. The lap nozzle 72 may be
located in an instrument panel of the vehicle 16 when the occupant
12 is seated in a front seat of the vehicle 16. The lap nozzle 72
may be located within a seat back when the occupant 12 is sitting
in a rear seat or a third row seat of the vehicle 16.
[0069] The sensitive portion 30 may be a foot portion. The first
nozzle 18 may be a foot nozzle. The first air stream 20 from the
foot nozzle may be a foot air stream. The foot nozzle may be
characterized as having a foot nozzle discharge area between 3 and
12.5 square centimeters. For heating, the foot nozzle flow rate may
preferably be between 2.3 liters per second (5 CFM) and 9.5 liters
per second (20 CFM) and the lap nozzle stream temperature may
preferably be between 35.degree. C. and 55.degree. C.
[0070] There may preferably be a foot nozzle for each foot of the
occupant. The foot nozzle may be located in an instrument panel of
the vehicle 16 when the occupant 12 is seated in a front seat of
the vehicle 16. The foot nozzle may be located under a seat when
the occupant 12 is sitting in a rear seat or a third row seat of
the vehicle 16.
[0071] The system 10 may further include a second nozzle 76 that is
configured to direct a second air stream 78 from the HVAC system
10. The second air stream 78 may be provided to maintain the
ambient temperature within the vehicle cabin 14. The second air
stream 78 is distinct from the first air stream 20. The stream
temperature of the first air stream 20 is distinct from a second
stream temperature. The second air steam may have a second air
stream temperature and a second air stream flow rate effective to
maintain the ambient temperature of the vehicle cabin 14 higher
than the comfortable temperature of 24.degree. C. when the HVAC
system 10 is cooling the vehicle cabin 14 and to maintain the
ambient temperature of the vehicle cabin 14 lower than 24.degree.
C. when the HVAC system 10 is heating the vehicle cabin 14.
[0072] The controller 28 may be configured to decrease the stream
temperature of the first air stream 20 and increase the second air
stream 78 temperature effective to decrease energy consumed by the
HVAC system 10 when energy available to the HVAC system 10 for
cooling is reduced. Alternatively, the controller 28 may be
configured to increase the stream temperature of the first air
stream 20 and decrease the second air stream 78 temperature
effective to decrease energy consumed by the HVAC system 10 when
energy available to the HVAC system 10 for heating is reduced. As a
non-limiting example, electrical energy available to the HVAC
system 10 to cool the occupant 12 may be limited in order to
improve the driving range of the electric vehicle. Therefore, the
controller 28 may increase the second air stream 78 temperature to
reduce the electrical energy required to maintain the ambient
temperature in the vehicle cabin 14. The controller 28 may then
decrease the first air stream 20 temperature in order to establish
the desired heat supply rate of the sensitive portion 30. The
electrical energy reduction realized by increasing the second
stream temperature may be greater than the electrical energy
increase realized by decreasing the stream temperature of the first
air stream 20, thereby providing a net energy savings to the HVAC
system 10 that may be used by the electrical drive system to
improve the EV driving range while still maintaining a comfortable
thermal environment for the occupant 12. Similar energy savings may
also be realized in IC engine vehicles wherein the energy for the
HVAC system 10 is derived from the IC engine.
[0073] The controller 28 may be configured to increase the flow
rate of the first air stream 20 and increase the second air stream
78 temperature effective to decrease energy consumed by the HVAC
system 10 when energy available to the HVAC system 10 for cooling
is reduced. Alternatively, the controller 28 may be configured to
increase the flow rate of the first air stream 20 and decrease the
second air stream 78 temperature effective to decrease energy
consumed by the HVAC system 10 when energy available to the HVAC
system 10 for heating is reduced. As a non-limiting example,
electrical energy available to the HVAC system 10 to cool the
occupant 12 may be limited in order to improve the driving range of
the electric vehicle. Therefore, the controller 28 may increase the
second air stream 78 temperature to reduce the electrical energy
required to maintain the ambient temperature in the vehicle cabin
14. The controller 28 may also increase the flow rate of the first
air stream 20 in order to establish the desired heat supply rate
for the sensitive portion 30. The electrical energy reduction
realized by increasing the second stream temperature may be greater
than the electrical energy increase realized by increasing the flow
rate of the first air stream 20, thereby providing a net energy
savings to the HVAC system 10 that may be used by the electrical
drive system to improve the EV driving range while still
maintaining a comfortable thermal environment for the occupant
12.
[0074] The controller 29 may be configured to decrease a flow rate
of the second air stream 78 effective to decrease energy consumed
by the HVAC system 10 when energy available to the HVAC system 10
is reduced.
[0075] The system 10 may further include a plurality of nozzles
configured to direct a plurality of streams of air from the HVAC
system 10 to a plurality of sensitive portions. In a non-limiting
example the head nozzle 18 may deliver the head air stream 20 to
the head portion 64 while the lap nozzle 72 delivers the lap air
stream 74 to the lap portion 70 and the chest nozzle 66 delivers
the chest air stream 68 to the chest portion 34.
[0076] A flow rate of at least one stream in the plurality of
streams of air may be reduced effective to decrease energy consumed
by the HVAC system 10 when energy available to the HVAC system 10
is reduced. The flow rate of at least one stream may be reduced to
no flow in order to decrease energy consumed by the HVAC system 10.
In a non-limiting example, electrical energy available to the HVAC
system 10 to cool the occupant 12 may be limited in order to
improve the driving range of the electric vehicle. Therefore, in a
heating, ventilation, and air conditioning system 10 with a head
nozzle 18, a chest nozzle 66 and a lap nozzle 72, the controller 28
may reduce the flow rate of the lap air stream 74, since the lap
portion 70 is the least sensitive portion of the body of the
occupant 12 that is being spot conditioned. As the energy available
to the HVAC system 10 is further reduced, the controller 28 may
stop the lap air stream 74 and reduce the flow rate of the chest
air stream 68 since the chest portion 34 is less sensitive than the
head portion 64. As the energy available to the HVAC system 10 is
yet further reduced, the controller 28 may stop the chest air
stream 68 while still providing the head air stream 20. This may
beneficially provide a net energy savings to the HVAC system 10
that may be used by the electrical drive system to improve the EV
driving range while providing spot conditioning to the most
thermally sensitive portion of the body of the occupant 12, the
head portion 64.
[0077] The system 10 may further include a plurality of nozzles
configured to direct a plurality of streams of air from the HVAC
system 10 to a plurality of seating locations within the vehicle
cabin 14. The system 10 may further include an occupant sensor in
communication with the controller 28 and configured to determine
whether an occupant 12 is sitting in a particular seating location.
If the controller 28 determines that a seating location is
unoccupied, the controller 28 will stop the air streams from the
nozzles directed to that seating location.
[0078] FIG. 8 illustrates a non-limiting method 100 of controlling
a heating, ventilation, and air conditioning system 10 to provide a
perceived comfortable ambient environment to an occupant 12 seated
in a vehicle cabin 14.
[0079] Step 110, IDENTIFY A SENSITIVE PORTION OF A BODY OF THE
OCCUPANT, may include identifying a portion of the body of the
occupant 12 that is more sensitive to heat loss than other portions
of the body. Identification of the sensitive portion 30 may be
based on models of the human body such as the Human Thermal Comfort
Model developed by Zhang et al., ibid to determine thermal comfort
sensitivity of body portions to the ambient temperature. Step 110,
IDENTIFY A SENSITIVE PORTION OF A BODY OF THE OCCUPANT, may be
based on a database of temperature sensitivity of various body
portions.
[0080] Step 112, DETERMINE AN AMBIENT TEMPERATURE OF THE VEHICLE
CABIN, may include determining an ambient temperature of the
vehicle cabin 14. The method 100 may further include disposing a
temperature sensor 52 within the vehicle cabin 14. The temperature
sensor 52 may be configured to measure the ambient air temperature
within the cabin 14.
[0081] Step 114, DETERMINE A DESIRED HEAT SUPPLY RATE FOR THE
SENSITIVE PORTION, may include determining a desired heat supply
rate for the sensitive portion 30. The desired heat supply rate may
include a steady-state heat supply rate based on a difference
between a comfortable heat loss rate for the sensitive portion 30
and an actual heat loss rate for the sensitive portion 30 at the
ambient temperature. The desired heat supply rate may further
include a transient heat supply rate for the sensitive portion 30.
The transient heat supply rate may diminish in magnitude based on
an elapsed time since a system start event.
[0082] Step 116, DETERMINE A COMFORTABLE SKIN TEMPERATURE FOR THE
SENSITIVE PORTION, may include determining a comfortable skin
temperature for the sensitive portion 30. The comfortable skin
temperature may also be based on models of the human body such as
the Human Thermal Comfort Model developed by Zhang et al., ibid.
Step 116, DETERMINE A COMFORTABLE SKIN TEMPERATURE FOR THE
SENSITIVE PORTION, may be based on a database of comfortable skin
temperature for various body portions.
[0083] Step 118, DETERMINE A FLOW RATE FOR A STREAM OF AIR AND A
STREAM TEMPERATURE FOR THE STREAM, may include determining a flow
rate for a stream of air and a stream temperature for the stream
based on at least the desired heat supply rate, the comfortable
skin temperature, a discharge area of a nozzle, a dispersion angle
of the nozzle, and a distance from the nozzle to the sensitive
portion 30. The steady state heat supply rate may be increased and
the flow rate for the stream of air may be decreased the when
energy available to the HVAC system is reduced.
[0084] Step 124, DETERMINE A LOCATION OF THE SENSITIVE PORTION, may
include determining a location of the sensitive portion 30. The
determination may be based on location information regarding the
sensitive body portions in relation to the nozzle, as a
non-limiting example azimuth and distance information. The location
information may be generalized so that the location information
encompasses the location of the sensitive portion 30 of a female
occupant in the 10.sup.th percentile of height and a male occupant
in the 90.sup.th percentile of height.
[0085] Step 120, DETERMINE A SEATED HEIGHT OF THE OCCUPANT, may
include determining a seated height of the occupant 12. Step 124,
DETERMINE THE LOCATION OF THE SENSITIVE PORTION, may include
determining the location of the sensitive portion 30 based on the
seated height. The determination of the location of the sensitive
portion 30 may be based on determining the seated height of the
occupant 12 by comparing anthropometric data, such as that
contained in Chapter 11 of "Human Engineering Guide to Equipment
Design", ibid. The method 100 may also include a step of disposing
a sensor 54 that is configured to determine a seated height of the
occupant within the vehicle cabin 14.
[0086] Step 122, DETERMINE A SEAT POSITION OF A SEAT OF THE
OCCUPANT, may include determining a seat position of a seat of the
occupant 12 and Step 124, DETERMINE THE LOCATION OF THE SENSITIVE
PORTION, may include determining the location of the sensitive
portion 30 based on the seat position.
[0087] Step 126, OPERATE THE NOZZLE TO DIRECT THE STREAM TO THE
LOCATION OF THE SENSITIVE PORTION, may include operating the nozzle
to deliver the stream to the location of the sensitive portion 30.
The nozzle may be articulated to aim the stream toward the location
of the sensitive portion. The stream may be characterized as having
the stream temperature and the flow rate necessary to establish the
desired heat supply rate at the sensitive portion 30.
[0088] Step 128, PROVIDE A HEAD NOZZLE CONFIGURED TO DIRECT THE
STREAM TOWARD THE HEAD PORTION, may include providing a head nozzle
18 configured to direct the stream toward the head portion 64. The
sensitive portion of steps 110, 114, 116, 124, and 126 may be a
head portion 64. The head nozzle 18 may be characterized as having
a head nozzle discharge area between 1.25 and 12 square
centimeters, a head nozzle to head portion distance between 4 times
a nozzle equivalent diameter and 10 times the nozzle equivalent
diameter, a head nozzle flow rate between 0.9 liters per second (2
CFM) and 3.3 liters per second (7 CFM), and a head nozzle stream
temperature between 22.degree. C. and 26.degree. C.
[0089] Step 130, PROVIDE A CHEST NOZZLE CONFIGURED TO DIRECT THE
STREAM TOWARD THE CHEST PORTION, may include providing a chest
nozzle 66 configured to direct the stream toward the chest portion
34. The sensitive portion of steps 110, 114, 116, 124, and 126 may
be a chest portion 34. The chest nozzle 66 may be characterized as
having a chest nozzle discharge area between 1.25 and 20 square
centimeters, a chest nozzle to chest portion distance between 8
times a nozzle equivalent diameter and 15 times the nozzle
equivalent diameter, a chest nozzle flow rate between 3.8 liters
per second (8 CFM) and 7.6 liters per second (15 CFM), and a chest
nozzle stream temperature between 22.degree. C. and 26.degree.
C.
[0090] Step 132, PROVIDE A LAP NOZZLE 72 CONFIGURED TO DIRECT THE
STREAM TOWARD THE LAP PORTION, may include the step of providing a
lap nozzle 72 configured to direct the stream toward the lap
portion 70. The sensitive portion 30 of steps 110, 114, 116, 124,
and 126 may be a lap portion 70. The lap nozzle 72 may be
characterized as having a lap nozzle discharge area between 10 and
45 square centimeters, a lap nozzle to lap portion distance between
8 times a nozzle equivalent diameter and 15 times the nozzle
equivalent diameter, a lap nozzle flow rate between 2.3 liters per
second (5 CFM) and 9.5 liters per second (20 CFM), and a lap nozzle
stream temperature between 22.degree. C. and 26.degree. C.
[0091] Step 134, PROVIDE A PLURALITY OF NOZZLES CONFIGURED TO
DIRECT A PLURALITY OF STREAMS OF AIR TO A PLURALITY OF SENSITIVE
PORTIONS, may include the step providing a plurality of nozzles
configured to direct a plurality of streams of air from the HVAC
system to a plurality of sensitive portions. The desired heat
supply rate for a more sensitive portion may be increased and the
desired heat supply rate for a less sensitive portion may be
decreased. The more sensitive portion may be over conditioned by
providing a heat supply rate for the sensitive portion greater than
the steady-state heat supply rate to achieve overall thermal
comfort. The desired heat supply rate for the less sensitive
portion may be decreased by reducing or eliminating the flow rate
of the air stream directed to the less sensitive portion.
[0092] Accordingly, a heating, ventilation, and air conditioning
system 10 and a method 100 of controlling a HVAC system 10 that is
configured to provide a perceived comfortable ambient environment
to an occupant 12 seated in a vehicle cabin 14 is provided. The
system 10 and method 100 determine the location of a thermally
sensitive portion 30 of the body of the occupant 12 and spot
condition the sensitive portion 30 by delivering an air stream to
that sensitive portion 30 that has a temperature and a flow rate
that effectively thermally isolates the sensitive portion 30 from
the ambient temperature of the vehicle cabin 14. Thus, it may be
possible to save energy required by the HVAC system 10 by
maintaining the vehicle cabin 14 at an ambient temperature higher
or lower than is typically required for occupant 12 comfort.
[0093] While this invention has been described in terms of the
preferred embodiments thereof, it is not intended to be so limited,
but rather only to the extent set forth in the claims that follow.
Moreover, the use of the terms first, second, etc. does not denote
any order of importance, but rather the terms first, second, etc.
are used to distinguish one element from another. Furthermore, the
use of the terms a, an, etc. do not denote a limitation of
quantity, but rather denote the presence of at least one of the
referenced items.
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